1. Field of the Invention
The present invention relates to an endoscope apparatus with a measurement function. Furthermore, the present invention relates to a method of measuring a subject.
Priority is claimed on Japanese Patent Application No. 2010-051917, filed Mar. 9, 2010, the content of which is incorporated herein by reference.
2. Description of Related Art
In gas turbines mainly used in aircraft, their internal portions reach a high temperature. This sometimes results in the production of a defect (burned portion) such as a burn or tarnish on a surface of a turbine blade. The size of the defect is one of the indices for determining whether to replace the blade or not, so the inspection of the defect is extremely important. An endoscope apparatus with a measurement function is used for inspecting blades. In the inspection of blades, the endoscope apparatus measures the defect based on an image where the defect is imaged (hereinafter, referred to as a measurement image) and displays a measurement result. A user checks the measurement result, and determines whether or not the blade needs replacing.
A function of a plane-based measurement is known as one of functions provided in an endoscope apparatus (refer to, for example, Japanese Unexamined Patent Application, First Publication No. H2-296209). In the plane-based measurement, a spatial distance (i.e., three-dimensional distance) between a virtual plane (i.e., base plane) determined by spatial coordinates of three points which are specified on a measurement screen by a user, and spatial coordinates of one point which is specified on the measurement screen by the user. The base plane is a plane at the defect position that approximates a surface of the measurement target when no defect exists. By performing the plane-based measurement, it is possible to obtain the depth of a concave portion, the height of a convex portion, or the like which exists on the surface of a measurement target.